I got the same problem as your problem and now I can fixed it but not working currectly with SMTP server (somrtime work good but sometime doesn't work). something like DSN for domain1.com still looking an old IP address or DSN for domain2.com is the same, I have to modify it by myself.

And now I'm fixed on domain1.com on server1.
The problem is domain1.com on server1 still lookup old IP address, I've to fix it point to new IP address, It works when I send an email to domain2.com on server2 but when I send from domain2.com from server2 to domain1.com on server1.
All sended email/message will lost.
Maybe my problem such like that tread above because I got the error message like that tread sometime but sometime not.